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The mechanism of ethylene biosynthesis and its role in horticultural crops and regulation and function of ethylene synthesis during ripening and senescence

乙烯生物合成机制及其在园艺作物中的作用及乙烯合成在成熟和衰老过程中的调控和功能

基本信息

批准号：
13660027
负责人：
HYODO Hiroshi
金额：
$ 2.24万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Ethylene plays an essential role in growth, development ; differentiation, and senescence of plants. In horticultural crops ethylene is closely involved in the mechanism of ripening and senescence. On the other hand, ethylene is rapidly produced in response to various kinds of stresses such as wounding and disease caused by infection with microorganisms. (1)Ethylene biosynthesis and its regulation during senescence of broccoli florets (flower buds): Broccoli is harvested while florets are still green and immature which are covered with green sepals. After harvest senescence proceeds rapidly in florets at ambient temperatures in which yellowing progresses due to chlorophyll degradation. The high levels of ascorbic acid (vitamin C) rapidly decline after harvest during senescence. The rate of ethylene production increased during senescence which was paralleled by the increase in ACC oxidase activity and its gene expression. The rate of ethylene biosynthesis in broccoli florets was regulat … More ed by the gene expression of ACC synthase and ACC oxidase after harvest. Harvesting broccoli causes the cessation of the transport of water, hormones, sugars, amino acids, and minerals from the mother plant and together with wounding by cutting the stem may result in triggering or accelerating senescence of the young flower organ of florets. (2)Ethylene biosynthesis and its mechanism in sweet potato root tissue infected by black rot fungus (Ceratocystis fimbriata): A large amount of ethylene is produced in sweet potato roots upon infection by black rot fungus. The pathway of ethylene biosynthesis was independent on methionine-ACC pathway that is widely operating in higher plants. We have found the new pathway for the synthesis of ethylene in sweet potato root tissue infected by the pathogen. The mechanism of the novel pathway is summarized as follows. In response to infection with the fungus, phospholipase A_2 is activated, liberating linolenic acid, which is hydroperoxidized by lipoxygeriase in the host tissue. Then, ethylradical is cleaved from the peroxidized linolenic acid, which is oxidized by cupric ion to yield ethylene. Ethylene produced may be involved in the activation of metabolism in sweet potato root tissue infected by the pathogen. Less

乙烯在植物的生长、发育、分化和衰老中起着重要作用。在园艺作物中，乙烯与成熟和衰老机制密切相关。另一方面，乙烯响应于各种应激（例如由微生物感染引起的创伤和疾病）而快速产生。（1）青花菜小花（花蕾）衰老过程中乙烯的生物合成及其调控：在青花菜小花仍为绿色和未成熟且被绿色萼片覆盖时收获青花菜。收获后，在环境温度下小花迅速衰老，其中由于叶绿素降解而变黄。高水平的抗坏血酸（维生素C）在收获后衰老期间迅速下降。衰老过程中乙烯产生速率增加，这与ACC氧化酶活性及其基因表达的增加有关。青花菜小花的乙烯合成速率受到调控， ...更多信息艾德受收获后ACC合酶和ACC氧化酶基因表达的影响。收获西兰花会导致来自母株的水、激素、糖、氨基酸和矿物质的运输停止，并且连同通过切割茎的创伤一起可能导致小花的幼花器官的触发或加速衰老。（2）黑腐菌侵染甘薯根组织中乙烯的生物合成及其机理：甘薯根在黑腐菌侵染后产生大量乙烯。乙烯生物合成途径不依赖于广泛存在于高等植物中的甲硫氨酸-ACC途径。我们发现了甘薯根组织中乙烯合成的新途径。新途径的机制总结如下。在对真菌感染的反应中，磷脂酶A_2被激活，释放亚麻酸，亚麻酸被宿主组织中的脂氧合酶过氧化氢。然后，乙基自由基从过氧化亚麻酸裂解，其被铜离子氧化以产生乙烯。乙烯的产生可能参与了甘薯根组织代谢的激活。少